1. Field of the Invention
This invention relates to improvements in dispenser carrying apparatus and more particularly to improvements in apparatuses for circumnavigating a dispenser about a pipe or the like.
2. Description of the Prior Art
In many instances, it is desirable to provide protective coatings for pipe sections, tanks, or other cylindrical objects buried in the ground or otherwise exposed to the environment or deleterious influences. While a variety of methods and apparatus have been devised to accomplish an objective of coating the outer surface of a pipe or tank, there remains a need for an apparatus, particularly a powered apparatus, useable in the field, directed toward achieving a uniform coating on the pipe particularly adjacent the exposed interface or joint between two adjacent pipe or tank sections after welding or other joining and sealing processes. This need is particularly significant in the absence heretofore of any apparatus for uniformly dispensing a powder coating such as powdered epoxy resin about the outer surface of the tank or pipe section of interest.
This need can be more fully appreciated, for example, from an understanding of a typical installation procedure used in fabricating a pipeline. Commonly, the pipe sections are pre-coated along their length with a protective coating, such as epoxy or other material resistant to the elements to which the pipe will be exposed. However, to facilitate fastening adjoining pipe sections, especially sections to be but welded together, an area adjacent the ends of each pipe sections usually are left uncoated, so that the coating material pre-coated on the pipe will not interfere with the welding processes. Then, after the weld has been effected, the areas adjacent the joint as well as the weld itself are coated, so that the entire length of the pipe formed is covered with a continuous protective coating.
In the past, the coating has been achieved simply by manually painting or spraying the coating material on the sections, and often, after the coating material is applied, it is heated, by such as induction heaters to cure the coating material or to enhance its durability and quality.
However, in such manual spraying or coating, it is particularly difficult, as well as time consuming, to achieve a suitable coat of uniform thickness for maximum protection. Furthermore, although the particular type of coating material used depends upon the particular installation of interest, it has been found that in many applications if the coating material is applied in powder form and subsequently cured, such as by heating, a particularly high quality coating can be achieved. Such powder application in the field or in remote regions where the actual welding takes place, however, presents additional problems in handling the material, depositing it upon the pipe, and, in general, in achieving a coat around the pipe of uniform thickness and quality.
As hereinafter set forth, the prior art fails to suggest any apparatus suitable for this need, especially without necessitating extensive handling and movement of the pipe sections prior and subsequent to the coating operation. Even where extensive handling and movement of the pipe or tank sections to be coated has not been necessary, the prior art devices are primarily directed to use with particular structures, such as the vertical tank as shown in U.S. Pat. No. 2,476,299. This patent discloses a relatively complex vertical tank or standpipe coating device, having a coating machine adjacent to the outer tank periphery, suspended by a cable hanging from a carriage mounted on top of the tank. To ensure contact between the coating machine and the periphery of the tank, a cable is passed around the tank with both ends secured by a clamp mounted on the coating machine. The device is primarily intended for use with tanks having substantial diameters; and its use is specifically directed to use with vertically positioned tanks.
Other pipe coating or painting devices have been disclosed; for example, U.S. Pat. No. 3,674,546, shows a coating device including a track carried vehicle for carrying a pipe to be coated past a stationary coating applicator located adjacent the tracks. The disclosure clearly provides that the entire length of pipe, including its junctions, be moved past the stationary coating applicator. A similar device, shown in U.S. Pat. No. 2,470,994, presents a relatively complex paint sprayer for a flag pole, which rides the longitudinal length of the implaced pole.
In view of the above, it is evident that the prior art fails to make any showing or suggestion of any apparatus specifically directed toward coating the interface between two adjacent pipe-like sections or of uniformly dispensing a powder about their peripheries.